Parameters optimization on surface roughness improvement of Zerodur optical glass using an innovative rotary abrasive fluid multi-jet polishing process

With the advance of contemporary technology, high precision surface finishing techniques for optical glasses are of great concern and developing to meet the requirements of the effective industrialized processes. Not only the used tools but also process parameters have great influence on the surface roughness improvements. In this paper, surface roughness improvement of Zerodur optical glass using an innovative rotary abrasive fluid multi-jet polishing process has been presented. For the same purpose, a tool for executing ultra precision polishing was designed and manufactured. Taguchi's experimental approach, an L₁₈ orthogonal array was employed to obtain the optimal process parameters. ANOVA analysis has also been carried out to determine the significant factors. It was observed that about a 98.33% improvement on surface roughness from (R_a) 0.360 μm to (R_a) 0.006 μm has been achieved. The experimental results show that a surface finished achieved can satisfy the requirements for optical-quality surface (R_a < 12 nm). In addition, the influence of significant factors on surface roughness improvement has been discussed in this study.     

Review on mechanism and process of surface polishing using lasers

Laser polishing is a technology of smoothening the surface of various materials with highly intense laser beams. When these beams impact on the material surface to be polished, the surface starts to be melted due to the high temperature. The melted material is then relocated from the ‘peaks to valleys’ under the multidirectional action of surface tension. By varying the process parameters such as beam intensity, energy density, spot diameter, and feed rate, different rates of surface roughness can be achieved. High precision polishing of surfaces can be done using laser process. Currently, laser polishing has extended its applications from photonics to molds as well as bio-medical sectors. Conventional polishing techniques have many drawbacks such as less capability of polishing freeform surfaces, environmental pollution, long processing time, and health hazards for the operators. Laser polishing on the other hand eliminates all the mentioned drawbacks and comes as a promising technology that can be relied for smoothening of initial topography of the surfaces irrespective of the complexity of the surface. Majority of the researchers performed laser polishing on materials such as steel, titanium, and its alloys because of its low cost and reliability. This article gives a detailed overview of the laser polishing mechanism by explaining various process parameters briefly to get a better understanding about the entire polishing process. The advantages and applications are also explained clearly to have a good knowledge about the importance of laser polishing in the future.     

无磨料低温抛光的工艺方法研究

对无磨料低温抛光这种全新的工艺方法进行了系统的研究,包括抛光设备、抛光冰盘的制备、工件盘的制备、抛光盘的修整、抛光后工件的清洗、抛光后表面粗糙度的测量等。并用此种方法对石英晶体进行了抛光实验,得到了Ra0．53mm的超光滑表面,结果证明这是一种获得超光滑表面的新方法。     

Effects of process parameters on surface roughness in abrasive waterjet cutting of aluminium

Abrasive waterjet cutting is a novel machining process capable of processing wide range of hard-to-cut materials. Surface roughness of machined parts is one of the major machining characteristics that play an important role in determining the quality of engineering components. This paper shows the influence of process parameters on surface roughness (R_a) which is an important cutting performance measure in abrasive waterjet cutting of aluminium. Taguchi’s design of experiments was carried out in order to collect surface roughness values. Experiments were conducted in varying water pressure, nozzle traverse speed, abrasive mass flow rate and standoff distance for cutting aluminium using abrasive waterjet cutting process. The effects of these parameters on surface roughness have been studied based on the experimental results.     

提高活塞表面光洁度的叶轮抛光工艺

通过对剪板机、折弯机产品活塞杆表面质量、加工原理分析及阐述,提出了"叶轮"抛光加工工艺及其在生产中的广泛应用。实践证明,"叶轮"抛光工艺能很好地满足活塞杆等高精度表面零件的设计要求。     

气-液-固三相磨粒流光整加工及其工艺参数优化

考虑用流体抛光法加工大尺度工件存在效率低下问题,本文提出了一种气-液-固三相磨粒流抛光方法。该方法在约束流场中引入微纳米气泡,利用气泡在溃灭时释放的能量加速驱动磨粒运动,从而有效提升抛光效率。实验显示:在加工过程中,离心泵的发热会导致流体黏度下降,进而影响工件近壁面的湍动能和动压力的大小及分布,而加工工件近壁面的湍动能和动压力会对表面纹理的均匀性和材料的去除效率有重要影响。针对上述实验结果,文中基于对磨粒流抛光机理的研究,提出一种通过改变入口流速来补偿温升带来的湍动能和动压力变化的方法,实验求得了抛光流体温度从20℃到60℃之间的9个均等点对应的最优入口流速值。实验表明,相对未加入气泡时,该抛光方法的加工效率得到提高,而调速补偿明显提升了工件表面加工质量。     

Surface roughness modeling in chemically etched polishing of Si (100) using double disk magnetic abrasive finishing

Abstract

The present paper focuses on proposing a new method for determining the surface roughness of chemically etched polishing of Si (100) using double disk magnetic abrasive finishing (DDMAF). Based on chemical etching in KOH solution Vicker’s hardness of Si (100) at different concentration of KOH was determined in context to chemical etching phenomenon. A mathematical relationship was established to relate Vicker’s hardness of Si (100) as a function of the concentration of KOH. The penetration depth of abrasive particle into Si (100) workpiece was determined considering viz; the normal force acting on the abrasive particle under the influence of magnetic flux density and Vicker’s hardness of etched Si (100). The other modeling variables such as wear constant, penetration area of the abrasive particle into Si (100) workpiece which is dependent on the penetration depth of abrasive particle was modified in terms of magnetic flux density and concentration of KOH. The process parameters such as working gap, abrasive mesh number and the rotational speed of the primary magnet were also considered in modeling the surface roughness. The results of surface roughness obtained by the model were also experimentally validated. The theoretical and experimental findings agreed well with each other.     

Experimental investigation of surface roughness and cutting ratio in a spraying cryogenic turning process

Abstract

Surface roughness is one of the most common criteria indicating the surface finish of the part, which depends on various factors including cutting parameters, geometry of the tool, and cutting fluid. One of the goals of using cutting fluids in machining processes is to achieve improved surface finish. In addition to high costs, commonly used cutting fluids cause dermal and respiratory problems to the operators as well as environmental pollution. The present article aims at investigating the effect of spray cryogenic cooling via liquid nitrogen on surface roughness and cutting ratio in turning process of AISI 304 stainless steel. Through conducting experimental tests, the effects of cutting speed, feed rate, and depth of cut on surface roughness and cutting ratio have been compared in dry and cryogenic turning. A total number of 72 tests have been carried out. Results show that cryogenic turning of AISI 304 stainless steel reduces surface roughness 1%–27% (13% on the average), compared to dry turning. The obtained results showed that the cutting ratio in cryogenic turning is averagely increased by 32% in comparison with dry turning, also that chip breakage is improved in cryogenic turning.     

Optimization of sandblasting process of complex 3D surface polishing using variable viscoelastic diamond particles abrasive

This article reports a novel and efficient diamond particles abrasive with tunable viscoelasticity for sandblasting polishing. Controlling the rust inhibitor content can change its viscoelasticity to adhere diamond particles on polymer materials. Using the sandblasting mechanism, the abrasive deform and slide on the workpiece surface, so that the diamond particles can cut onto the surface peaks of the workpiece. Thus, the complicated morphology can be rapidly and precisely polished. The friction generated by the abrasive on the surface of the workpiece will cause the rust inhibitor solution to evaporate, resulting in reduced viscosity, which makes the diamond particles gradually fall off from the abrasive. Applying Taguchi method, the optimal parameters for viscosity and injection angle were identified. The surface roughness was found to decrease from Ra?=?1.47?μm to Ra?=?0.2?μm in 3?min. The two kinds of complex concave surfaces of different materials were polished by this innovative composite diamond particles abrasive with the optimal parameter values, which has been verified to have 40 times higher efficiency than the traditional manual polishing.     

铝合金高速切削表面粗糙度影响因素研究

为有效降低高速切削中铝合金的表面粗糙度值,通过多因素正交试验和单因素试验对各铣削参数进行研究,结果显示:各参数对铝合金表面粗糙度影响程度从大到小的顺序是:切削深度、主轴转速、每齿进给量、行距,且转速为18000r/min,每齿进给量为0.075mm,行距和每齿进给量一致,选择较小的切削深度时,在铝合金表面可获得较好的加工质量。     

三维表面粗糙度的表征和应用

表面粗糙度会直接影响零部件的耐磨性、密封性以及抗腐蚀性等,是评定机械加工和产品质量的重要指标。现代科技水平的不断提高对零件表面性能的要求也日益严苛。传统的二维表面粗糙度的测量和表征已经不再能够满足技术发展的要求,三维表面粗糙度由于能够更加全面、真实地反映工件表面的状态而受到人们的重视,成为研究热点。本文回顾了三维表面粗糙度的发展历史,系统地介绍了三维表面粗糙度参数及标准的发展现状,分析了表面形貌与功能特性的联系,概述了三维粗糙度参数在制造业、生物医疗、摩擦学与材料科学等领域的广泛应用,并进一步指出了三维表面粗糙度表征和应用的发展方向。未来随着相关研究(比如,三维测量的溯源性、重复性、参数表征体系等问题)的深入以及三维表面测量手段的发展,三维表面粗糙度参数也将不断完善和推广,并更多地与实际功能相结合来预测并指导生产,确保工件的表面质量。     

Tool wear and its effect on surface roughness in diamond cutting of glass soda-lime

For the technology of diamond cutting of optical glass, the high tool wear rate is a main reason for hindering the practical application of this technology. Many researches on diamond tool wear in glass cutting rest on wear phenomenon describing simply without analyzing the genesis of wear phenomenon and interpreting the formation process of tool wear in mechanics. For in depth understanding of the tool wear and its effect on surface roughness in diamond cutting of glass, experiments of diamond turning with cutting distance increasing gradually are carried out on soda-lime glass. The wear morphology of rake face and flank face, the corresponding surface features of workpiece and the surface roughness, and the material compositions of flank wear area are detected. Experimental results indicate that the flank wear is predominant in diamond cutting glass and the flank wear land is characterized by micro-grooves, some smooth crater on the rake face is also seen. The surface roughness begins to increase rapidly, when the cutting mode changes from ductile to brittle for the aggravation of tool wear with the cutting distance over 150 m. The main mechanisms of inducing tool wear in diamond cutting of glass are diffusion, mechanical friction, thermo-chemical action and abrasive wear. The proposed research makes analysis and research from wear mechanism on the tool wear and its effect on surface roughness in diamond cutting of glass, and provides theoretical basis for minimizing the tool wear in diamond cutting brittle materials, such as optical glass.     

Modeling the effects of abrasive size, surface oxidizer concentration and binding energy on chemical mechanical polishing at molecular scale

No conclusive results have been proposed for the influence of the abrasive particle size on the material removal during the chemical mechanical polishing (CMP). In this paper, a mathematical model as a function of abrasive size and surface oxidizer concentration is presented for CMP. The model is proposed on the basis of the molecular-scale removal theory, probability statistics and micro contact mechanics. The influence in relation to the binding energy of the reacted molecules to the substrate is incorporated into the analysis so as to clarify the disputes on the variable experimental trends on particle size. The predicted results show that the removal rate increases sub-linearly with the abrasive particle size and oxidizer concentration. The model predictions are presented in graphical form and show good agreement with the published experimental data. Furthermore, variations of material removal rate with pressure, pad/wafer relative velocity, and wafer surface hardness, as well as pad characteristics are addressed. Results and analysis may lead further understanding of the microscopic material removal mechanism from molecular-scale perspective.     

On the prediction of surface roughness in the hard turning based on cutting parameters and tool vibrations

This research work concerns the elaboration of a surface roughness model in the case of hard turning by exploiting the response surface methodology (RSM). The main input parameters of this model are the cutting parameters such as cutting speed, feed rate, depth of cut and tool vibration in radial and in main cutting force directions. The machined material tested is the 42CrMo4 hardened steel by Al₂O₃/TiC mixed ceramic cutting tool under different conditions. The model is able to predict surface roughness of Ra and Rt using an experimental data when machining steels. The combined effects of cutting parameters and tool vibration on surface roughness were investigated while employing the analysis of variance (ANOVA). The quadratic model of RSM associated with response optimization technique and composite desirability was used to find optimum values of cutting parameters and tool vibration with respect to announced objectives which are the prediction of surface roughness. The adequacy of the model was verified when plotting the residuals values. The results indicate that the feed rate is the dominant factor affecting the surface roughness, whereas vibrations on both pre-cited directions have a low effect on it. Moreover, a good agreement was observed between the predicted and the experimental surface roughness. Optimal cutting condition and tool vibrations leading to the minimum surface roughness were highlighted.     

固着磨料加工碳化硅反射镜的材料去除率及表面粗糙度的理论研究

本文基于固着磨料加工碳化硅反射镜的微观作用原理，理论上定量分析探讨了金刚石磨料压入碳化硅工件的深度对材料去除率、光学元件表面粗糙度的影响，分别获得了材料去除率数学模型及粗糙度的仿真计算结果。通过去除率及粗糙度的实验与理论模型的对比结果来看，实验值虽与理论值有偏差，但基本稳定在同一数量级内，由此验证了理论分析的正确性。固着磨料工艺的这一易于理论预测的特性对实际的光学加工有着极为重要的意义，因此这种较为新颖的固着磨料工艺在碳化硅反射镜加工领域内有着广阔的应用前景。     

中等口径光学非球面的高效研抛技术

介绍了一种弹性模抛光与小磨头修正抛光相结合的两步研抛法实现中等口径光学非球面表面的快速抛光。利用弹性模预抛光来保证小工具抛光模型的准确稳定,并采用补偿的方法减小弹性模抛光对面形精度的破坏作用。然后利用优化的小磨头修正残留的表面误差来提高抛光精度。应用上述方法加工非球面,在较短的抛光周期中,获得的面形P-V精度达0.35μm。     

枪匣表面机器人砂带抛光刀位点轨迹规划研究和试验验证

围绕某军工单位生产的机器人砂带抛光枪匣加工系统,基于等参数线法,在枪匣表面生成刀位点轨迹,针对机器人砂带抛光枪匣表面刀轴矢量的控制方法进行了研究;通过对空间自由曲面相关特性分析,实现了机器人砂带抛光系统刀位点数据的生成和枪匣表面磨削路径的合理规划;在机器人仿真平台上,对枪匣表面砂带抛光进行了虚拟仿真,并运用磨头可浮动的砂带抛光机对研究方法进行了试验验证,试验结果表明:按照等参数线法生成的磨削路径和刀轴矢量控制方法进行抛光,不仅可以保证枪匣型面的一致性,而且能够极大地改善枪匣表面质量,最终实现枪匣表面高效、高质量的抛光加工。     

表面粗糙度测量方法综述

表面粗糙度是机械加工中描述表面微观形貌非常重要的一个参数,表面粗糙度测量技术是现代精密测试计量技术的一个重要组成部分。综述了接触式和非接触式两类测量方法,着重介绍了非接触式测量中的几种测量方法的测量原理及其优缺点。     

Some speculations on the mechanisms of abrasive grinding and polishing

The mechanisms of grinding, a predominantly fracture mechanism in brittle material, and polishing, a predominantly plastic shearing mechanism, appear quite different. However, in a number of cases, it can be shown that the difference between the two mechanisms can be triggered by differences in depth of cut and abrasive size. Results are presented from recent polishing research that tend to support a physico-chemical interaction model involving aqueous diffusion, internal hydrolysis and ion exchange mechanisms that may explain the plastic to brittle transition in silicate materials. The model would seem to have clear implications for both low-scatter polishing and fine machining of silicate materials.